Colpitts oscillators

The design of the high stability and low noise oscillators is the special sort of knowledge, and there are quite many books about that. This stuff is covered well in the professional books on the frequency synthesizers.

The SPICE model of transistor is OK, but it has somewhat 50 or so parameters. Of course, most of those parameters are not even specified by the manufacturers. There is also other problem with SPICE simulation of RF: damn slow. The timestep is determined by the carrier frequency, and the duration of a run is determined by the modulation.

Vladimir Vassilevsky DSP and Mixed Signal Design Consultant

Nothing wrong with that. But isn't that supposed to be complete at the end of high school? There is an alarming number of "kids" in our area who haven't made up their minds while pushing 30 (!).

Ok, there is indeed another good one here on the shelf and it's in English: Rohde's "Communications Receivers", McGraw-Hill. Top notch stuff. If he just hadn't picked that ugly bonbon-green for the cover.

Yup. I remember a guy who smoked out a Pentium doing that.

Is that an older edition of

---Joel

Mine is this one:

Different Co-Author and 1988 edition. I never keep the dust covers, maybe that had a different color. Chapter 7 goes into great detail about spectral purity of oscillators including amplitude stabilization.

...

Thanks Joerg.

Surprising how many people have written books on receiver design... I can definitely see the attraction.

I have never seen much less heard of either of those authors,but from your description, i would most prefer Hayward because of the C1/C2 analysis is more instructive - probably allows one to go to the "extreme" of tha "class C" operation previously mentioned. How about a common emitter, grounded collector design running at minimum distortion with maximum (transistor) temp stability and taking the output via a lo-Z tap on a resonant LC tank at the collector? Totally load independent...

I knew I would work in electronics when I was in Jr. High School, back in the mid '60s. I figured I might as well, since I was already repairing car radios and phonographs, after school.

contrast

It is not totally independent but fairly good.

You can also frequency multiply in the collector section. This makes the operating frequency even more load independent. The impedance between the emitter and base at the harmonic is very low so anything that transfers back sees nearly a dead short. It works best if the oscillator is "gm reduction" or AGC controlled and doesn't bottom.

Mine in Zivildienst. Getting dumped into real life after 13 years of school is a very sobering and personality-building experience. I wouldn't want to have missed it.

robert

Richard The Dreaded Libertarian writes in newsgroup sci.electronics.politics :

Limiting. Personally, I'll rip off any good idea, I don't care about the provenance.

I think the point was, he couldn't afford medical insurance. So when he NEEDED medical attention it, er, cost an arm and a leg.

I'm in the UK. Our "medical insurance" costs us an average of half yours for approximately the same level of cover, and 100% of our citizens are covered. I think ~15% of your citizens cannot afford medical insurance. I'm not sure how many are covered by Medicare and how many earn just a bit too much to qualify for that, but I've heard that until the current credit crunch, medical fees were perhaps the largest cause of bankruptcy in the US?

Incidentally, I'm not saying our National Health Service is perfect. Far from it. Just that it's better value for money, on average. It works like this. Left to themselves, insurance companies will charge sky-high fees to insure risky customers, which tends to discourage those folk from insuring. If everyone is forced to pay insurance as we do here in the UK, the nation-wide not-for-profit insurance system called the NHS can afford to invest in a specialist centre for rare conditions, to serve a large area of the country. Now let's say you have a history of a rare neurological disease in your family, for example a tendency to vote Conservative. In the US, you would probably have to pay above the odds for insurance... here, everyone's fees are pooled and, remember, the NHS is *not* trying to minimise payouts so there are neurologists available for everyone, though sometimes there's an unacceptable wait due to resource problems and people who can afford it prefer to go private. (Of course the story is more complex than this, there are tradeoffs and internal competition - do we buy an expensive MRI machine or hire another consultant this year - but you get the idea.) In an odd twist, since the European health services have reciprocal links, some people are beginning to go to e.g. France for some types of operation, where the queues are shorter, and sending the bill to the UK NHS.

Oh, apparently the Singapore system is even better than ours, albeit slightly more complex.

I think at this point it is traditional to claim "ah yes. Colpitts was good Socialist circuit design."

Whilst I'm here, I'd just like to say thank you to everyone for all the informative posts in this newsgroup (yes even you Richard), I'm learning lots.

Canadians and other foreigners regularly troop to the US when they have a critical medical need.

Wonder why?

...Jim Thompson

"Jim Thompson" wrote in message news: snipped-for-privacy@4ax.com...

If you've got money, the U.S. is probably the fastest and easiest place to get any procedure you'd like, regardless of how complex or exotic.

If you don't have money... well, in the same film that Rich was referencing ("Sicko"), one storyline involves a young woman (I believe she's a college student) who has cancer and, being uninsured, finds herself a "friend" in Canada who's willing to call her his "domestic partner" and thereby get her cancer drugs through the Canadian national healthcare system. While that's clearly fradulent, I expect that many people in the same position would behave similarly.

---Joel

Michael Moore makes up stories to suit his own purposes.

My youngest son had no insurance, but received the best treatment available right up to the very day he died from colon cancer.

Except for the pain-relieving medications most of the treatment was a total waste of time (and the hospital and doctor's expense)... I recognized "Stage 4" the instant I saw the colonoscopy pictures :-(

...Jim Thompson

Speaking of firing up the Weller - you guys may get a laugh out of a coil I made for a Colpitts. I'll post a picture of the coil and jury rig to wind it on abse.

Ed

On Tue, 8 Jan 2008 13:09:26 -0800, "Joel Koltner" wrote: ..

Butler (overtone) circuits can work really well in my experience. Analog Devices have a nice 125MHz 5th o.t. appnote with a Butler.

Joop

P.S. There is no such thing as a parallel resonant crystal oscillator.

Smirk. Wonder how many here will argue with you?

BTW, I've preferred the Butler configuration since the mid '60's.

...Jim Thompson

Exactly. Taking money away from the people who earn it to pay the bills of those who don't is so obviously wrong that anyone who doesn't see the wrongness of it must be feeble-minded or brain-damaged.

Taxation _IS_ theft, you know. If you don't believe this, just choose to not participate some time (It was supposed to be "voluntary", right?) and they WILL take it from you by force, using violence on you if they find it "necessary".

If that's not theft, then we have different dictionaries.

Thanks, Rich

On Wed, 09 Jan 2008 08:56:59 -0800, Joel Koltner wrote: ...

This is _precisely_ the reason that socialist _anything_ is wrong. Everybody just takes whatever they can get, and the ones who bother to take care of themselves get their money taken away anyway.

Well, when Hillary gets elected and turns the country socialist, we'll learn, albeit the hard way, much like the Soviet Union.

Then again, would it be so bad if the federal bureaucracy went broke? ;-)

But, regardless, people should pay their own bills, unless they're feeble-minded or incompetent, in which case as wards of the state they should be institutionalized.

Thanks, Rich